Saint George is a real historical figure venerated since the early centuries of Christianity — but the dragon he's now best known for slaying appears nowhere in the earliest accounts of his life. It is a much later medieval addition, and understanding where it actually came from changes very little about George's genuine sainthood and everything about how we should read the story.
George is generally understood by historians as a genuine early Christian martyr — likely a Roman soldier executed around 303 CE during Emperor Diocletian's persecution of Christians. His veneration as a saint spread widely and early across the Christian world, but the dragon-slaying story is entirely absent from these earliest accounts of his martyrdom.
The dragon legend enters the tradition much later, becoming genuinely widespread through Jacobus de Voragine's hugely popular 13th-century collection of saints' lives, the Legenda Aurea ("Golden Legend") — one of medieval Europe's true bestsellers, copied and translated everywhere, which carried George's now-famous dragon story into common knowledge across the continent roughly a thousand years after his actual death.
In the story, a dragon terrorises a city (traditionally located in Libya, called Silene), demanding regular sacrifices — first sheep, then, as those run out, townspeople chosen by lottery. Eventually the lot falls to the king's own daughter. George arrives just as she is being led out to her fate, wounds the dragon with his lance, and — in a distinctive and often-overlooked detail — does not kill it outright. Instead, he leads the now-docile dragon into the city on a leash improvised from the princess's own girdle, offering to finish it off only if the townspeople agree to convert to Christianity. They do, en masse, and George completes the slaying.
A borrowed narrative shape: the story's structure — hero arrives to save a princess from a sea or land monster demanding sacrifice — closely echoes the much older Greek myth of Perseus and Andromeda, set in a similar North African coastal region. Most scholars treat this as a plausible narrative influence rather than coincidence: an existing heroic story-pattern grafted onto the real historical martyr centuries after his death, with explicit Christian conversion added as the story's new moral centre.
An unusually widespread patronage: Saint George became the patron saint of England (his red-cross-on-white flag still England's own national flag today), of the country of Georgia (named for him), of Catalonia, of Portugal, and the city of Moscow, whose own official emblem depicts George spearing a dragon. He is also the namesake and patron of England's most prestigious chivalric order, the Order of the Garter — a single dragon-slaying legend that became genuinely foundational to an entire continent's national and civic identity.